This invention relates to a method of fabricating a sealing cover for use in fabricating an hermetically sealed container including a semiconductor device.
As is well known, it has become conventional hermetically to seal a semiconductor device in the cavity of a metallic or ceramic body to protect the device from adverse atmospheric effects and to provide physical protection. In the case of a ceramic body, a metallic ring is usually imbedded in or fused into the body surrounding the cavity containing the semiconductor device.
Heretofore it has been the practice hermetically to seal the semiconductor device in the cavity of the body by placing a preformed ring of heat-fusible material, such as a gold-tin eutectic solder, on the body and surrounding the cavity and, in the case of a ceramic body, with an imbedded metallic ring in registry with that ring, and heating the assembly to fuse the ring to the cover and to the body.
The solder material of the ring may be brittle and its dimensions are so small that the ring is very fragile and extremely difficult to handle during assembly. Because of the difficulty of handling such sealing rings, it has also been difficult to ensure accurate registration between the ring and the periphery of the cover and of the cavity in which the semiconductor device is mounted. As a consequence, there has been a substantial yield loss in the finished semiconductor assemblies due to the defects in the hermetic seal.